Refrigerator evaporator



April L. w. ATCHISON 1,996,605

REFRIGERATOR EVAPORATOR Filed Sept. 20, 19:54

lnvqntof: :2 I Leonard \X/.Atchison,

i At fovneg Patented Apr. 2, 1935 "UNITED STATES REFRIGERATOR EVAPORATORLeonard W. Atchison, Schenectady, N. Y., as signor to General ElectricCompany, a corporation of New York Application September 20, 1934,Serial No. 744,794

13 Claims.

My invention relates to flooded type evaporators for refrigeratingsystems.

Flooded type evaporators comprise a chamber containing a body of liquidvaporizable refrigerant and the liquid refrigerant is vaporized in thechamber upon the absorption of heat from the body to be cooled. It hasbeen found in practice that the temperature of the liquid refrigerant inthe evaporator must rise several degrees above the boiling pointthereof, at the pressure existing in the evaporator before vaporization,or boiling, is started below the-surface of the liquid. This phenomenais commonly known as superheating of the liquid. It is, of course,desirable to avoid this superheating, both in order to increase theefiiciency of the machine and to improve the accuracy of control of thetemperature of the evaporator.

It is an object of my invention to provide a flooded evaporator forrefrigerating systems in which boiling or vaporization of the liquidrefrigerant contained therein will be initiated without substantialsuperheating thereof, and. in which vaporization of the liquidrefrigerant will be initiated in such manner as to promote rapidcirculation of the liquid refrigerant in the evaporator.

Further objects and advantages of my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a partof this specification.

For a better understanding of my invention, reference may be had to theaccompanying drawing in which Fig. 1 is a perspective view of arefrigerating system including an evaporator embodying my invention;Fig. 2 is a detailed sectional view of a portion of the evaporator shownin Fig. 1; Fig. 3 is a perspective view of a modified form of evaporatorembodying my invention; Fig. 4 is a detailed view of a portion of theevaporator shown in Fig. 3; and Fig. 5 is a detailed view of a modifiedform of the evaporator shown in Fig. 3.

Referring to the drawing, in Fig. 1, I have shown a refrigerating systemincluding an evaporator embodying my invention. In this system a motoranda compressor are arranged in a hermetically sealed casing In. Gaseousrefrigerant ing across the walls of the evaporator I4, the adjacent endsof the sinuous passages I8 and I9 being connected by a plurality ofducts 20. The sheet I6 is preferably slightly larger than the sheet I5and its edges are folded over the adjacent edges of sheet l5. The sheetsare welded or otherwise secured together along the edges and between therefrigerant passages and the sheets are then bent so as to have aninverted L-shaped form, thus providing a freezing shelf |8w upon whichfreezing trays or other articles may be conveniently supported within arefrigerator cabinet in which the evaporator is used.

In order to fiood the evaporator M with liquid refrigerant and removevaporized refrigerant therefrom, I. provide a spherical header 2| hav-'ing a depending cylindrical portion 22. The lower portion of thespherical header is connected by conduit 23 to the upper end of thesinuous passage |8 in the shelf Ba, and the cylindrical portion 22 isconnected by a conduit 24 to the sinuous passage IS in the evaporator atthe lowermost bend therein. The header 2| is maintained about half fullof liquid refrigerant, the level of' portions of the sinuous refrigerantpassage |9,'

which induces a fiow of liquid refrigerant throughthe sinuous passageI9, ducts 20, sinuous passage l8, and the connection 23 to a header 2|,the liquid refrigerant returning to the evaporator |4 through theconnection 24 to the sinuous passage I9 of the evaporator. In thismanner the injection'of the liquid refrigerant at |3a into theevaporator I4 induces rapid circulation of liquid refrigerant therefromthrouglf the header 2| and refrigerant vaporized by the absorption ofheat is quickly carried to the header where it rises above the liquidlevel therein and is withdrawn from the header through the suctionconduit 25 by the compressor within the casing I0. This suction conduit25 extends above the level of liquid refrigerant in the header 2|, so asto withdraw vaporized refrigerant without withdrawing liquid refrigeranttherefrom. The foregoing described refrigerating machine construction isnot my invention, but is the invention of Christian Steenstrup, and isdescribed and claimed in his application Serial No. 733,044, filed June29, 1934, and assigned to the General Electric Company, assignee of thisapplication.

It will be noted that the lower leg of the sinuous passage I9 is not inthe direct path of refrigerant circulation described above, so thatvaporization of liquid refrigerant is retarded and superheating of theliquid refrigerant occurs therein. In accordance with my invention Ihave modified the construction of this lower leg of sinuous passage I9in order to facilitate the initiation of vaporization of liquidrefrigerant therein to avoid superheating of the liquid refrigerant andto promote rapid circulation of refrigerant therethrough. As best shownin Fig. 2, I do this by providing an indentation 26 in the upper wall ofthe lower leg of the sinuous passage l9 near the closed end 2'! thereof.A body of vaporized refrigerant 28 is trapped between the indentation 26and closed end 21 by the liquid refrigerant 29 which normally fills thesinuous passage l9. In this way, a body of vaporized refrigerant isprovided below the upper level of liquid refrigerant in the evaporatorand in contact with an unbroken free surface 30 of liquid refrigerant. Ihave found that liquid refrigerant will vaporize much more easily from asurface exposed to a vapor than a surface exposed to the wall of apassage. As a consequence, vaporization of the liquid refrigerant 29 isfacilitated on the exposed surface 30 and vaporization begins in theevaporator without substantial superheating. The bubbles of vaporizedrefrigerant formed on the surface 30 move along the lower leg of sinuouspassage IQ of evaporator l4 and pass upwardly through sinuous passage l9to the point l3a where they are entrained by the entering liquidrefrigerant. This movement of bubbles of vaporized refrigerant throughthe lower portion of sinuous passage l9 sets up a rapid circulation ofrefrigerant therein and aids in the recirculation of liquid refrigerantfrom the conduit 24.

Another form of evaporator embodying my invention is shown in Fig. 3.This evaporator includes a horizontal cylindrical header 3| anddepending reentrant passages32 connected thereto. Liquid refrigerant issupplied to the header 3| through liquid line 33 and flows from theheader through the passages 32, the header 31 being maintained abouthalf full of liquid refrigerant thus flooding the passages 32. Freezingtrays or other articles to be cooled may be conveniently supported inthe evaporator. As the liquid refrigerant contained in the passagesabsorbs heat bubbles of vaporized refrigerant are formed in the passages32 and rise to the header 3| causing circulation of liquid refrigerantfrom the header 3| through the passages 32, the direction of circulationbeing ordinarily upward on the side of the evaporator which is at thehighest temperature. This circulation of liquid refrigerant quicklycarries refrigerant vaporized by the absorption of heat to the header3|, where it rises above the liquid level therein and is drawn 01fthrough suction line 34.

In accordance with my invention the construction of the passages 32 hasbeen modified to facilitate the initiation of vaporization of liquidrefrigerant therein without substantial superheating and to promoterapid circulation of refrigerant therethrough. As best shown in Fig. 4,I do this by providing grooved plates 35 with flattened ends 36 whichare welded or otherwise fastened to the interior walls of the passages32, the open ends of the grooves being directed downwardly to form vaporpockets or traps 35a. The grooved plates 35 may be provided in any orall of the passages 32. In Fig. 3 they are shown as being placed in allexcept the end passages. A body of vaporized refrigerant 31 is confinedby each of the grooved plates 35 below the upper level of the liquidrefrigerant in the header 3|, being in contact with the free surfaces 38of the liquid refrigerant. Asdescribed above, this surface of liquidrefrigerant exposed to vaporized refrigerant within the traps 35afacilitates the ebullition or vaporization of refrigerant below thesurface of the main body thereof. When the temperature of the liquidrefrigerant is raised to its boiling point, bubbles of vaporizedrefrigerant are formed at the surfaces 38 in the pockets 35a, escapebelow the pockets, and bubble up through the passages 32. It isadvantageous to place the pockets 35a in the side of the passages 32adjacent the highest ambient temperature for in this way the bubbles ofrefrigerant formed at the surface 38 help to promote the circulation ofliquid refrigerant induced by the vaporization of refrigerant throughoutthe passages 32.

In Fig. I have shown an alternative form of refrigerant vapor pocketwhich may be used in such an evaporator as that shown in Fig. 3. Thisvapor pocket is formed by utilizing inverted cups v39 which are securedto the upper interior wall of the passages 32 in the lower horizontalportions thereof. The cups 39 contain bodies of vaporized liquidrefrigerant 40 which are exposed to free surfaces 4| of the liquidrefrigerant contained in the passages 32. I prefer to place the cups 39on the side of the center line of the passages 32 which is nearest thehighest ambient temperature in order to aid circulation of liquidrefrigerant through the evaporator, induced in the main portion of thepassages by the vaporization of liquid refrigerant.

It will be apparent to those skilled in the art that other forms ofpockets or traps may be provided to confine a body of vaporizedrefrigerant below the surface of the liquid refrigerant in anevaporator, in which the vaporized refrigerant in the pockets is incontact with a surface of substantial area of liquid refrigerant inorder to promote boiling or vaporization of the liquid refrigerantwithout substantial superheating thereof.

While I have shown a particular embodiment of my invention in connectionwith evaporators of compression refrigerating machines, I do not desiremy invention to be limited to the particular construction shown anddescribed, and I intend in the appended claims to cover allmodifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. An evaporator of the flooded type for refrigerating apparatuscontaining a body of vaporizable liquid refrigerant, and means forinitiating vaporization of said body of liquid refrigerant, said meansproviding a body of vaporized refrigerant exposed to a free surface ofsaid liquid refrigerant and retained thereby below a portion of saidbody of liquid refrigerant.

I 2. An evaporator of the flooded type for refrigerating apparatuscontaining a quantity of vaporizable liquid refrigerant, and means forinitiating vaporization of said liquid refrigerant, said means providinga body of vaporized refrigerant confined below the upper surface of saidliquid refrigerant in contact with an unbroken free surface thereof ofsubstantial area.

3. An evaporator for refrigerating apparatus of the flooded typeincluding a header and a refrigerant containing portion connectedthereto below the normal liquid level in said header, said header andsaid refrigerant containing portion containing a body of vaporizableliquid refrigerant, and means for initiating vaporization of said bodyof liquid refrigerant, said means providing with a free surface of saidliquid refrigerant below the upper surface thereof to initiatevaporization of said liquid refrigerant.

5. An evaporator for refrigerating apparatus of the flooded typeincluding a header and a reentrant passage connected thereto having aportion below the normal liquid level in said header, a non-reentrantpassage connected to said first mentioned passage and provided with aclosed outer end, said header and passages containing a body ofvaporizable liquid refrigerant, and means including a constrictedsection in said non-reentrant passage adjacent said closed end thereoftrapping a body of vaporized refrigerant between said constrictedsection and said closed outer end in contact with a free surface of saidliquid refrigerant below the upper surface thereof for inducingcirculation of said liquid refrigerant through said non-reentrantpassage.

6. An evaporator for refrigerating apparatus of the flooded typeincluding a heater and a reentrant passage connected thereto having aportion thereof below the normal liquid level in said header, anon-reentrant passage connected to said first mentioned passage andhaving a closed outer end, said header and passages containing a. bodyof vaporizable liquid refrigerant, an inlet connection provided with aninjector in said reentrant passage for inducing circulationof saidliquid refrigerant therethrough from said header, and means including aconstricted section in said non-reentrant passage adjacent the closedouter end thereof trapping a body of vaporized refrigerant between saidconstricted section and said closed end in contact with a free surfaceof said liquid refrigerant below the upper surface thereof for inducingcirculation of said liquid refrigerant through said non-reentrantpassage.

7. An evaporator for refrigerating apparatus of the flooded typeincluding a header and a reentrant passage connected thereto having aportion thereof below the normal liquid level in said header, anon-reentrant passage connected to said header, said header and passagescontaining a. body of vaporizable liquid refrigerant, an inletconnection provided with an injector in said reentrant passage forinducing circulation of said liquid refrigerant therethrough from saidheader, andmeans confining a body of vaporized refrigerant in saidnon-reentrant passage in contact with a free surface of said liquidrefrigerantbelow the upper surface thereof for inducing circulation ofsaid liquid refrigerant through said nonreentrant passage.

refrigerant below the upper surface thereof for inducing circulation ofsaid liquid refrigerant through said passage.

9. An evaporator for refrigerating apparatus of the flooded typeincluding a header and a reentrant passage connected thereto having aportion thereof below the normal liquid level in said header, saidheader and passage containing a body of vaporizable liquid refrigerant,and means for aiding the circulation of said liquid refrigerant throughsaid passage produced by vaporization of refrigerant therein, said meansincluding means in the section of said passage adjacent the highestambient temperature for confining a body of vaporized refrigerant insaid passage in contact with a free surface of said liquid refrigerantbelow the upper surface thereof. v,

10. An evaporator for refrigerating apparatus of the flooded typeincluding a header and a reentrant passage connected thereto having aportion thereof below the normal liquid level in said header, a body ofvaporizable liquid refrigerant, and means for inducing circulation ofsaid liquid refrigerant through said passage, said means including agrooved metallic member having a closed upper end secured to a verticalinterior wall of said passage for confining a body of vaporizedrefrigerant in contact with a free surface of said liquid refrigerantbelow the upper surface thereof.

11. An evaporator for refrigerating apparatus of the flooded typeincluding a header and a reentrant passage connected thereto having aportion thereof below the normal liquid level in said header, saidheader and passage containing a body of vaporizable liquid refrigerant,and means for aiding the circulation from said header of said liquidrefrigerant through said passage induced by vaporization ofliquidrefrigerant therein, said means including a trap secured to aninterior vertical wall of said passage on the leg thereof adjacent thehighest ambient temperature and a body of vaporized refrigerant bonfinedin said trap in contact with a free surface of said liquid refrigerantbelow the upper surface thereof.

12. An evaporator for refrigerating apparatus of the flooded typeincluding a header and a reentrant passage connected thereto having aportion thereof below the normal liquid level in said header, saidheader and passage containing a body of vaporizable liquid refrigerant,and means for inducing circulation of said liquid refrigerant throughsaid passage, said means including an inverted cup secured to aninterior wall of said passage adjacent the lowermost portion thereof forconfining abodyof vaporized refrigerant in contact with a free surfaceof said liquid refrigerant below the upper surface thereof.

13. An evaporator for refrigerating apparatus of the flooded typeincluding a header and a reentrant passage connected thereto having aportion thereof below the normal liquid level in said header, saidheader and passage containing a body of vaporizable liquid refrigerant,and means for aiding the circulation of said liquid refrigerant throughsaid passage induced by the vaporization of liquid refrigerant therein,said means including an inverted cup for confining a body of vaporizedrefrigerant in contact with a free surface of saidliquid refrigerantbelow the upper surface thereof, said cup being secured to an interiorwall of said passage and displaced from the center thereof to the sideadjacent the highest ambient temperature.

LEONARD W. ATCHISQN.

